南秦岭迭部地区硅质岩成因及富铀建造研究

发布时间：2018-04-05 23:05

本文选题：硅质岩　切入点：碳硅泥岩富铀建造　出处：《核工业北京地质研究院》2015年硕士论文

【摘要】：迭部铀矿田是我国典型的碳硅泥岩型铀矿田,区内分布数个铀矿床、矿点。这些矿床主要分布于志留纪地层中,并普遍显示出构造及地层控矿特征。笔者在前人研究的基础上,对区内志留纪碳硅泥岩建造进行了详细的野外地质调研、镜下观察和扫描电镜测试以及矿物学和地球化学分析,重点研究了碳硅泥岩富铀建造中硅质岩成因及铀矿物在硅质岩中的赋存状态,探讨了碳硅泥岩富铀建造的形成机理。通过论文工作,取得了以下主要成果和认识。(1)岩石学、矿物学及地球化学研究显示,研究区志留纪碳硅泥岩建造中的硅质岩为热水沉积成因。早-中志留世硅质岩的形成古环境为具深大断裂(裂谷)边缘海环境,中志留世硅质岩的形成古环境可能为具深大断裂(裂谷)的边缘海向小洋盆过渡环境。(2)地球化学分析表明,志留纪时期硅质岩中的铀部分来源于下伏中酸性火山岩,部分由陆源物质带入。(3)矿物学及扫描电镜分析测试表明,硅质岩中的铀矿物是以沥青铀矿的形式存在的。铀矿物局部与金属硫化物共生共同被有机炭的变种炭质(可能为石墨)所吸附,充填于石英颗粒中的微孔隙及微裂隙中。与铀矿物共生的元素为Ni、Mo、V、As等元素。(4)以硅质岩成因为约束条件,结合碳酸盐岩、陆源碎屑岩形成理论及研究区构造等前人研究成果,探讨了碳硅泥岩富铀建造的形成机理。
[Abstract]:Dibu uranium ore field is a typical carbon-silicon mudstone type uranium ore field in China. Several uranium deposits and ore sites are distributed in the area.These deposits are mainly distributed in Silurian strata and generally show structural and ore-controlling characteristics.On the basis of previous studies, detailed field geological investigation, microscopic observation, scanning electron microscopy, mineralogical and geochemical analysis of Silurian carbon-silicon mudstone formation were carried out in this area.The genesis of siliceous rocks and the occurrence of uranium minerals in siliceous rocks during the uranium-rich formation of carbon-siliceous mudstone are studied. The formation mechanism of uranium-rich formation of carbon-siliceous mudstone is discussed.Through the work of this paper, we have obtained the following main achievements and understandings. 1) Petrology, mineralogy and geochemistry show that the siliceous rocks in Silurian Carbonitic mudstone formation in the study area are of hydrothermal sedimentary origin.The paleoenvironment of early and Middle Silurian siliceous rocks is a marine environment with deep and large faults (rifts) margin.The Paleoenvironment of the Middle Silurian siliceous rocks may be the transitional environment of the marginal sea to the small ocean basin with deep and large faults (rift). Geochemical analysis shows that some of the uranium in Silurian siliceous rocks originated from the underlying intermediate-acid volcanic rocks.The results of mineralogy and SEM analysis show that the uranium ore in siliceous rocks exists in the form of asphaltene uranium ore.Uranium minerals are symbiosis with metallic sulfides and are adsorbed by the variant carbon (possibly graphite) of organic carbon and filled in micropores and fractures in quartz particles.The formation mechanism of uranium-rich formation of carbon-siliceous mudstone is discussed based on the formation theory of carbonate rock, continental clastic rock and the tectonics of the studied area.
【学位授予单位】：核工业北京地质研究院
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：P619.14;P588.244

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